National Institute for Health and Welfare, Oulu, Finland.
APMIS. 2011 Feb;119(2):135-42. doi: 10.1111/j.1600-0463.2010.02703.x. Epub 2010 Dec 1.
Xylitol inhibits the growth of Streptococcus pneumoniae. In clinical trials, xylitol decreased the occurrence of acute otitis media in day-care children, but did not decrease nasopharyngeal carriage of pneumococci. We hypothesized that xylitol inhibits biofilm formation of pneumococci, and measured biofilm formation and gene expression levels of the capsule gene cpsB and two other genes: autolysin encoding gene lytA and competence gene comA in different growth media in vitro. Twenty pneumococcal isolates were grown on polystyrene plates for 18 h in test media containing 0.5% xylitol, 0.5% glucose, 0.5% xylitol and 0.5% glucose, 0.5% fructose, 0.5% xylitol and 0.5% fructose or brain heart infusion (BHI) medium supplemented with 10% horse serum. Gene expression levels were measured after 5 h of growth using a relative quantification method with calibrator normalization. Exposure to xylitol lowered OD values, which were used as an indication of biofilm, compared with BHI medium, but when the medium was supplemented with glucose or fructose, biofilm formation was enhanced and the inhibitory effect of xylitol on biofilm formation was not observed. Xylitol also lowered lytA expression levels. Changes in biofilm formation in response to different sugar compounds may partly explain the efficacy of xylitol to prevent acute otitis media in previous clinical trials.
木糖醇抑制肺炎链球菌的生长。在临床试验中，木糖醇降低了日托儿童急性中耳炎的发生，但并未降低肺炎球菌的鼻咽携带率。我们假设木糖醇抑制肺炎球菌生物膜的形成，并在体外不同生长培养基中测量生物膜的形成和荚膜基因 cpsB 及另外两个基因：自溶素编码基因 lytA 和感受态基因 comA 的基因表达水平。将 20 株肺炎链球菌分离株在含有 0.5%木糖醇、0.5%葡萄糖、0.5%木糖醇和 0.5%葡萄糖、0.5%果糖、0.5%木糖醇和 0.5%果糖或补充有 10%马血清的脑心浸液（BHI）培养基的聚苯乙烯平板上培养 18 小时，用于测试培养基。使用相对定量方法并以校准物归一化来测量培养 5 小时后的基因表达水平。与 BHI 培养基相比，暴露于木糖醇会降低 OD 值，这是生物膜的指示物，但当培养基中添加葡萄糖或果糖时，生物膜形成增强，并且观察不到木糖醇对生物膜形成的抑制作用。木糖醇还降低了 lytA 的表达水平。对不同糖化合物的生物膜形成的变化可能部分解释了木糖醇在先前临床试验中预防急性中耳炎的功效。
